1. Field of the Invention
This invention pertains generally to image processing, and more particularly to processing of image line structures.
2. Description of Related Art
Of increasing importance is the need to detect vanishing points in the presence of parallel line segments in an image. Vanishing points may be used to calibrate cameras and detect road and obstacles for automatic navigation. As shown in FIG. 1, a vanishing point is the intersection point 14 in the image plane 10, 12 of all parallel lines in 3-D space when imaged by a perspective (e.g., pin-hole) camera. Each set of parallel lines has its own vanishing point. FIG. 2 illustrates three images 16, 18, and 20 having challenges for determining a vanishing point. Image 20 is representative of multiple vanishing points in an image, e.g. different sets of parallel lines 24 may produce multiple vanishing points. Other difficulties include images not having enough lines to compute a vanishing point, errors in estimating lines, and clutters and ill-defined lines 22 in images 16 and 18 may appear as computation noise.
One attempt to address vanishing point estimation is through Hough transform. However, this is a computationally expensive technique that has insufficient accuracy, and requires many lines. Another attempt is Bayesian with RANSAC, which is also highly complex. While shorter lines may be used, it still requires many lines to work.
Accordingly, an object of the present invention is to provide improved systems and methods for accurately detecting vanishing points in a variety of images, including images with clutters and ill-defined lines, while requiring minimal computational power. At least some of these objectives will be met in the following disclosure.